Package com.mckoi.database

Class V2MasterTableDataSource

java.lang.Object
com.mckoi.database.V2MasterTableDataSource
public final class V2MasterTableDataSource extends Object
A MasterTableDataSource that is backed by a non-shared com.mckoi.store.Store object. The store interface allows us a great deal of flexibility because we can map a store around different underlying devices. For example, a store could map to a memory region, a memory mapped file, or a standard random access file.

Unlike V1MasterTableDataSource, this manages data and index information in a single store which can be backed by a single file in the file system.

The structure of the store comprises of a header block that contains the following information; 

       HEADER BLOCK
   +-------------------------------+
   | version                       |
   | table id                      |
   | table sequence id             |
   | pointer to DataTableDef       |
   | pointer to DataIndexSetDef    |
   | pointer to index block        |
   | LIST BLOCK HEADER pointer     |
   +-------------------------------+

Each record is comprised of a header which contains offsets to the fields in the record, and a serializable of the fields themselves.

Author:
Tobias Downer

  • Field Details

    • table_id

      protected int table_id
      An integer that uniquely identifies this data source within the conglomerate.

    • is_closed

      protected boolean is_closed
      True if this table source is closed.

    • table_def

      protected DataTableDef table_def
      A DataTableDef object that describes the table topology. This includes the name and columns of the table.

    • index_def

      protected DataIndexSetDef index_def
      A DataIndexSetDef object that describes the indexes on the table.

    • table_indices

      protected com.mckoi.database.MultiVersionTableIndices table_indices
      A multi-version representation of the table indices kept for this table including the row list and the scheme indices. This contains the transaction journals.

    • column_rid_list

      protected com.mckoi.database.RIDList[] column_rid_list
      The list of RIDList objects for each column in this table. This is a sorting optimization.

    • DATA_CELL_CACHING

      protected boolean DATA_CELL_CACHING
      Set to false to disable cell caching.

    • cache

      protected final com.mckoi.database.DataCellCache cache
      A reference to the DataCellCache object.

    • column_count

      protected int column_count
      The number of columns in this table. This is a cached optimization.

    • garbage_collector

      protected com.mckoi.database.MasterTableGarbageCollector garbage_collector
      Manages scanning and deleting of rows marked as deleted within this data source.

    • blob_store_interface

      protected BlobStoreInterface blob_store_interface
      An abstracted reference to a BlobStore for managing blob references and blob data.

    • root_lock_key

      protected String root_lock_key
      The keys we use for Database.stats() for information for this table.

    • total_hits_key

      protected String total_hits_key

    • file_hits_key

      protected String file_hits_key

    • delete_hits_key

      protected String delete_hits_key

    • insert_hits_key

      protected String insert_hits_key

  • Constructor Details

    • V2MasterTableDataSource

      public V2MasterTableDataSource(TransactionSystem system, com.mckoi.database.StoreSystem store_system, com.mckoi.database.OpenTransactionList open_transactions, BlobStoreInterface blob_store_interface)
      The Constructor.

  • Method Details

    • open

      public void open(String file_name) throws IOException
      Opens an existing master table from the file system at the path of the conglomerate this belongs to. This will set up the internal state of this object with the data read in.
      Throws:
      IOException

    • scanForLeaks

      public void scanForLeaks() throws IOException
      Looks for any leaks in the file. This works by walking through the file and index area graph and 'remembering' all areas that were read. The store is then checked that all other areas except these are deleted.

      Assumes the master table is open.

      Throws:
      IOException

    • checkAndRepair

      public void checkAndRepair(String file_name, UserTerminal terminal) throws IOException
      Performs a complete check and repair of the table. The table must not have been opened before this method is called. The given UserTerminal parameter is an implementation of a user interface that is used to ask any questions and output the results of the check.
      Throws:
      IOException

    • toString

      public String toString()
      For diagnostic.
      Overrides:
      toString in class Object

    • getSystem

      public final TransactionSystem getSystem()
      Returns the TransactionSystem for this table.

    • Debug

      public final DebugLogger Debug()
      Returns the DebugLogger object that can be used to log debug messages.

    • getTableName

      public TableName getTableName()
      Returns the TableName of this table source.

    • getName

      public String getName()
      Returns the name of this table source.

    • getSchema

      public String getSchema()
      Returns the schema name of this table source.

    • makeTableFileName

      protected static String makeTableFileName(TransactionSystem system, int table_id, TableName table_name)
      Creates a unique table name to give a file. This could be changed to suit a particular OS's style of filesystem namespace. Or it could return some arbitarily unique number. However, for debugging purposes it's often a good idea to return a name that a user can recognise.

      The 'table_id' is a guarenteed unique number between all tables.

    • minimalTableDataSource

      protected TableDataSource minimalTableDataSource(IntegerListInterface master_index)
      Creates a minimal TableDataSource object that represents this MasterTableDataSource. It does not implement the 'getColumnScheme' method.

    • setupDataIndexSetDef

      protected void setupDataIndexSetDef()
      Sets up the DataIndexSetDef object from the information set in this object. This will only setup a default IndexSetDef on the information in the DataTableDef.

    • setupDataTableDef

      protected void setupDataTableDef(DataTableDef table_def)
      Sets up the DataTableDef. This would typically only ever be called from the 'create' method.

    • loadInternal

      protected void loadInternal()
      Loads the internal variables.

    • storeSystem

      protected com.mckoi.database.StoreSystem storeSystem()
      Returns the StoreSystem object used to manage stores in the persistence system.

    • doOpeningScan

      protected void doOpeningScan() throws IOException
      This is called by the 'open' method. It performs a scan of the records and marks any rows that are uncommitted as deleted. It also checks that the row is not within the master index.
      Throws:
      IOException

    • clearAllRootLocks

      protected void clearAllRootLocks()
      Clears all root locks on the table. Should only be used during cleanup of the table and will by definition invalidate the table.